The FBI's Clinton Foundation investigation was based on the book 'Clinton Cash' — and fueled by secret recordings

U.S. Democratic presidential nominee Hillary Clinton speaks at a campaign rally in Sanford Thomson Reuters The FBI launched its investigation into the Clinton Foundation based on news stories and information in the book "Clinton Cash," The New York Times reported on Tuesday, citing law enforcement officials.

The detail was included in a larger story about the FBI's decision to announce it was looking into new documents related to the Hillary Clinton email investigation — which was closed in July — and how it broke with its policy over the summer to refrain from publicizing cases about either candidate so close to the election.

Those cases centered on former Donald Trump campaign manager Paul Manafort's ties to Russian interests in Ukraine and the Clinton Foundation.

Both cases are still open, according to The Times. The probe into Manafort's foreign dealings are based largely on his work advising the former president of Ukraine and his pro-Russian political party, which earmarked $12.7 million in undisclosed cash payments for the former Trump campaign manager between 2007 and 2012, according to ledgers obtained by The Times.

The investigation into the Clinton Foundation, meanwhile, was first inspired by the book "Clinton Cash," published in 2015 and written by a Clinton critic, according to law enforcement officials. The book claimed the foundation traded favors and access for money while Clinton served in the State Department between 2009 and 2013.

The Clinton Foundation has accepted millions of dollars from foreign actors including Saudi Arabia, Qatar, and the United Arab Emirates. But the money was donated either before or after Clinton's tenure as secretary of state, according to PolitiFact.

The cover. Clinton Cash

Peter Schweizer, the author of "Clinton Cash" and an editor at large at the alt-right media outlet Breitbart — whose executive chairman, Stephen Bannon, took a leave of absence to be CEO of the Trump campaign — told NBC in April 2015 that he didn't have direct evidence proving that Hillary Clinton traded favors for money while she was at the State Department.

Developments since last week have laid bare strife both within the FBI and between the FBI and the Justice Department in multiple inquiries involving Clinton.

Some agents had obtained secret recordings of a suspect in a public-corruption case talking about deals the Clintons allegedly made using their private charity, The Wall Street Jounral reported on Thursday.

The agents therefore thought they had strong enough evidence, beyond what was outlined in "Clinton Cash", to move forward with a case.

But corruption prosecutors within the public-integrity section of the Justice Department, who are not politically appointed, reportedly pressured the bureau to drop the investigation, however. Investigators were told to stand down, and some within the FBI have blamed the agency's deputy director Andrew McCabe for caving to pressure from the Justice Department.

The prosecutors were apparently worried that they would be perceived as trying to influence the outcome of the election if they pursued the Clinton Foundation investigation with no hard evidence of criminal wrongdoing, both The Journal and The Times reported this week.

Adding to that perception last weekend was the revelation that the FBI had not obtained a separate warrant to sift through the roughly 650,000 Clinton emails found on disgraced former Rep. Anthony Weiner's laptop before announcing on Friday that the emails existed. The FBI eventually obtained a warrant over the weekend.

The FBI, investigating whether Weiner sent inappropriate messages to underage girls, subpoenaed his laptop in late September. He shared the laptop with his now estranged wife and top Clinton aide Huma Abedin, whose emails to and from Clinton are now being reviewed by the agency.

The Justice Department asked the FBI not to disclose the discovery of the emails to Congress so close to the November 8 election, according to The Times, but Comey wrote to his employees on Friday that he felt "an obligation to do so given that I testified repeatedly in recent months that our investigation was completed."